1. Technical Field
The present invention relates to an electromagnetic actuator and, more particularly, to a comparably small sized electromagnetic actuator using for such as automotive vehicle, for driving a reflecting mirror of a radar, for example.
2. Background Art
FIG. 8 and 9 are the schematic views showing an actuator according to a prior art. More in detail, FIG. 8 is the actuator classified as a voice coil type using a pair of the electromagnetic driving elements. Each of the electromagnetic driving elements consists of a magnet 2 installed on a bottom surface of a fixed cylindrical core 1, a bar shaped core 3 set on the magnet 2, a movable coil 4 installed in a ring shaped gap formed between the bar shaped core 3 and the cylindrical core 1 and a driven member 5 connected with the moving coil 4. The driven member 5 is installed free of rotation centering a rotating axis 7 supported by a bearing 6 and is driven by the movable coil 4.
In the actuator of the voice coil type, the driven member 5 is able to be driven in a direction of up and down by a driving force generated perpendicular to the movable coil according to a direction and a magnitude of a current through the movable coil 4. However, there are some disadvantages in using the movable coil 4 as depicted in the following. For example, a wiring 4a to the moving coil 4 is necessary, and, moreover, the moving coil 4 is needed to be light in weight for high speed operation. Accordingly, some constraints arise such as in increasing a number of turns or in enlarging a wire diameter of the movable coil 4, and so an adequate magnetic flux by the movable coil 4 is hard to be obtained. To cope with these problems, strengthening a force of the magnet 2, and reducing a magnetic resistance of the cylindrical core 1 and making the ring shaped gap smaller between the movable coil 4 and the cylindrical core 1 are inevitable for enlarging an electromagnetic driving force of the electromagnetic driving element. Resultantly, a high accuracy in fabricating the electromagnetic driving element becomes absolutely necessary.
FIG. 9 is an actuator classified as a solenoid type using a pair of the electromagnetic driving elements. Each of the electromagnetic driving elements consists of a fixed cylindrical coil 8 installed inside of the cylindrical core 1 and a movable core 9 fixed to the driven member 5, wherein the movable core 9 is installed to be attracted into the inside of the fixed coil 8. As above explained, although the actuator of the solenoid type is structurally simple, it has some weak points in a high speed control of the driven member 5 wherein a driving direction of the movable core 9 is limited to an attracting direction by the fixed coil 8, and a weight of a moving part is heavy due to the movable core 9.
In view of the above, it is the object of the present invention to provide an electromagnetic actuator wherein a driving force for a movable component fixed to a driven member is continuously controlled by a control coil fixed to a fixed component, a weight of the movable component is smaller and a high fabricating accuracy becomes is not required.
An electromagnetic actuator according to the present invention is equipped with, at least, an electromagnetic driving element for driving a driven member,
said electromagnetic driving element comprises a movable component fixed to the driven member and a fixed component facing said movable component,
said movable component includes a movable magnet with the first magnetic pole of the first magnetic polarity and the second magnetic pole of the second magnetic polarity,
said fixed component includes a fixed magnet with the first magnetic pole of the first magnetic polarity and the second magnetic pole of the second magnetic polarity installed wherein the first magnetic pole of the fixed magnet opposes to the first magnetic pole of said movable magnet so as to give an electromagnetic repulsive force to said movable magnet,
said fixed component also includes a control coil for generating an electromagnetic controlling force according to an exciting current, said control coil is installed between the first magnetic pole of said fixed magnet and the first magnetic pole of said movable magnet,
wherein said movable magnet is controlled by a totalized electromagnetic force of said electromagnetic repulsive force and said electromagnetic controlling force.
According to the electromagnetic actuator, as the movable magnet of the movable component is driven by the totalized electromagnetic force of the electromagnetic repulsive force by the fixed magnet of the fixed component and the electromagnetic controlling force by the control coil of the fixed component, the totalized electromagnetic force for the movable magnet is possible to be controlled continuously by the control coil. Moreover, as the driving force is adequately obtained by increasing the number of turns and enlarging the wire diameter of the control coil which is installed to the fixed component, a cutoff in weight of the movable magnet is possibly and a high fabricating accuracy of the fixed component becomes unnecessary.
The electromagnetic actuator according to the present invention has a configuration, wherein the control coil is installed between the first magnetic pole of said fixed magnet and the first magnetic pole of said movable magnet, apart both from the first magnetic poles of said fixed magnet and said movable magnet.
According to this configuration, as the control coil is installed between the first magnetic pole of the fixed magnet and the first magnetic pole of the movable magnet apart from the first magnetic poles of both magnets, a decrease in a magnetism keeping ability of the fixed magnet due to a magnetic flux of the control coil is mitigated and the electromagnetic repulsive force can be adequately given from the fixed magnet to the movable magnet.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein a plate of a magnetic material is disposed on the second magnetic pole of said fixed magnet.
According to this configuration, as the second magnetic pole of the fixed magnet is installed to a plate made of a magnetic material, a magnetic coupling is strengthened both between the fixed magnet and the movable magnet and between the control coil and the movable magnet, leading to give the electromagnetic repulsive force and the electromagnetic controlling force to the movable magnet to a larger extent.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein the control coil is turned around a center line between the first magnetic pole of said fixed magnet and the first magnetic pole of said movable magnet.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein a control core is installed between the first magnetic poles of said fixed magnet and the movable magnet, and said control coil is turned around said control core.
According to these configuration, as the control coil is turned around a center line between the first poles of the fixed magnet and the movable magnet, or the control coil is turned around the control core installed between the first magnetic poles of the movable magnet and the fixed magnet, the magnetic flux by the control coil is more effectively given to the movable magnet, leading to give the electromagnetic controlling force to a larger extent.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein one end of said control core is installed opposing to the first magnetic pole of the movable magnet through a gap, and the other gap is formed between the opposite end of said control core and the first magnetic pole of said fixed magnet.
According to this configuration, as one end of the control core opposing to the first magnetic pole of the movable magnet through a gap and the other gap is formed between the opposite end of the control core and the first magnetic pole of the fixed magnet, an improvement in a controllability of the electromagnetic controlling force by the control coil is possible by decreasing an effect of the magnetic flux by the control coil from both the movable magnet and the fixed magnet.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein the electromagnetic controlling force is changed for changing the totalized electromagnetic force according to a change in a magnitude, at least, of said exciting current through said control coil.
According to this configuration, as the totalized electromagnetic force is controlled by changing, at least, the magnitude of the exciting current of the control coil, the totalized electromagnetic force is possible to be continuously controlled by changing the magnitude of the exciting current being continuously.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein said exciting current of said control coil is changed in its magnitude and direction for changing the electromagnetic controlling force in its magnitude and direction leading to change said totalized electromagnetic force.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein said totalized electromagnetic force, according to the change of the magnitude and the direction of said exciting current of said control coil, is adjusted within a range for said electromagnetic repulsive force being given from the fixed component to said movable magnet.
Furthermore, the electromagnetic actuator according to the present invention has a configuration, wherein said totalized electromagnetic force is changed according to the change of the magnitude and the direction of said exciting current of said control coil, from the state that said fixed component gives said electromagnetic repulsive force to the state that fixed component gives an electromagnetic attractive force to said movable magnet.
According to these configuration, as the totalized electromagnetic force is controlled by changing the direction and the magnitude of the exciting current, the totalized electromagnetic force is possible to be controlled continuously in a wider range by changing the direction and the magnitude of the exciting current continuously. In this case, when the totalized electromagnetic force is adjusted in a range wherein the electromagnetic repulsive force is given from the fixed component to the movable component, the totalized electromagnetic force is possible to be adjusted widely in the range. And, moreover, the totalized electromagnetic force is possible to be more widely adjusted from the state of the electromagnetic repulsive force to the state of the electromagnetic attractive force for giving from the fixed component to the movable component.
Furthermore, an electromagnetic actuator according to the present invention comprising:
a driven member installed free of sway centering a supporting point,
a first electromagnetic driving element installed at one end of said driven member to the supporting point for driving said driven member, and
a second electromagnetic driving element installed at the other end of said driven member to the supporting point for driving said driven member,
said first electromagnetic driving element and said second electromagnetic driving element respectively includes a movable component fixed to said driven member and a fixed component opposing to its corresponding movable component,
each movable component has a movable magnet with the first magnetic pole of the first magnetic polarity and the second magnetic pole of the second magnetic polarity,
each fixed component has a fixed magnet with the first magnetic pole of the first magnetic polarity and the second magnetic pole of the second magnetic polarity installed wherein the first magnetic pole of the fixed magnet opposes to the first pole of its corresponding movable magnet so as to give an electromagnetic repulsive force to its corresponding movable magnet, and
each fixed component also has a control coil for generating an electromagnetic controlling force according to an exciting current, said each control coil is installed between the first magnetic pole of said fixed magnet and the first magnetic pole of said movable magnet,
wherein each movable magnet of said first and second electromagnetic elements is controlled by a totalized electromagnetic force of said electromagnetic repulsive force and said electromagnetic controlling force.
According to the electromagnetic actuator, the driving force for the driven member can be controlled continuously by the coils of the fixed components of the first electromagnetic element and the second electromagnetic element. Moreover the driving force for the driven member is adequately obtained by increasing the number of turns and enlarging the wire diameter of the control coils which are installed to the fixed components, then a cutoff in weight of each movable component is possibly and a high fabricating accuracy of each fixed component become unnecessary. As each control coil is installed between the first magnetic pole of the fixed magnet and the first magnetic pole of the movable magnet apart from the first magnetic poles of both magnets, a decrease in a magnetism keeping ability of the fixed magnet due to a magnetic flux of the control coil is mitigated and the electromagnetic repulsive force can be adequately given from the fixed magnet to the movable magnet.
The electromagnetic actuator according to the present invention is also configured, wherein the control coils of said first electromagnetic driving element and said second electromagnetic driving element are associatively controlled.
The electromagnetic actuator according to the present invention is also configured, wherein when said first electromagnetic driving element is controlled by its control coil to increase its electromagnetic repulsive force to its corresponding movable magnet, said second electromagnetic driving element is controlled by its control coil to decrease the electromagnetic repulsive force to its corresponding movable magnet.
The electromagnetic actuator according to the present invention is also configured, wherein when said first electromagnetic driving element is controlled by its control coil to increase its electromagnetic repulsive force to its corresponding movable magnet, said second electromagnetic driving element is controlled by its control coil so as to decrease the electromagnetic repulsive force and generate an electromagnetic attractive force to its corresponding movable magnet.
According to these configurations, in the electromagnetic actuator wherein the control coils of the first and second electromagnetic elements are associatively controlled, a direction or an angle of the driven member can be controlled based on a balance between the driving forces given by the first and second electromagnetic elements, in the electromagnetic actuator wherein when the first electromagnetic driving element is controlled by its control coil to increase its electromagnetic repulsive force to its corresponding movable magnet, the second electromagnetic driving element is controlled by its control coil to decrease the electromagnetic repulsive force to its corresponding movable magnet, a direction or an angle of the driven member can be controlled based on a balance between the electromagnetic repulsive forces given by the first and second electromagnetic elements, and in the electromagnetic actuator wherein when said first electromagnetic driving element is controlled by its control coil to increase its electromagnetic repulsive force to its corresponding movable magnet, said second electromagnetic driving element is controlled by its control coil so as to decrease the electromagnetic repulsive force and generate an electromagnetic attractive force to its corresponding movable magnet, a direction or an angle of the driven member can be controlled with more wide range based on a balance between the electromagnetic repulsive forces given by the first and second electromagnetic elements.
The electromagnetic actuator according to the present invention is also configured, wherein said control coils of the first electromagnetic driving element and the second electromagnetic driving element are independently controlled.
According to the configuration, the required driving for the driven member can be obtained by the independent control for each control coil, and an adjustment of resonant frequency in a mechanical driving system for the driven member can be obtained.